1. Field of the Invention
The present invention relates to an optical disc device for recording and/or playback of optical discs such as DVDs, CDs, and the like, and relates in particular to an optical disc device having an improved disc clamper for clamping the optical disc.
2. Description of Prior Art
In optical disc devices that employ, as recording media, optical discs, such as compact discs (CDs), digital versatile discs (DVD), Blu-Ray discs (BDs), and the like, laser light emitted by an optical pickup is focused onto a recording face of the optical disc to record data, and (or) laser light irradiating the recording face and reflected therefrom is detected to play back information.
In optical disc devices of the prior art, a traverse chassis on which an optical pickup and a turntable have been installed is attached at the back edge thereof in a vertically rotatable manner to a loader chassis. Above the turntable, a disc clamper is rotatably attached in an opening of a clamper support of a main chassis. When the optical disc is placed on a disc tray and fed in between the turntable and the disc clamper, the traverse chassis is lifted (rotated upward) by a cam slider, and the optical disc is caused to rotate with the rim of the center opening of the optical disc clamped by the turntable and the disc clamper, while the optical disc is irradiated with a laser beam from the optical pickup, to record or playback information.
One type of optical disc clamper system employed in an optical disc device of this kind is a magnet system, in which a magnet and a yoke are embedded within the disc clamper, while another yoke is provided on the upper face of the turntable, the optical disc being clamped between this disc clamper and the turntable. The purpose of the yokes is to minimize leakage of magnetic force produced by the magnetic member of the magnet.
A disc clamper of conventional magnet design will be described with reference to FIG. 6. A disc clamper of conventional magnet design is provided with a first member (lower clamper) 80 as shown in FIG. 6A, a second member 90 (upper clamper) as shown in FIG. 6B, a magnet, and yoke. For example, the magnet and the yoke are positioned on the first member 80 in that order, and then covered with the second member 90 in such a manner that the magnet and the yoke are sandwiched between the first member 80 and the second member, whereupon the first member 80 and the second member 90 are fastened together to complete assembly of the disc clamper of magnetic design.
The assembly process for a conventional disc clamper shall now be described in detail. Firstly, the first member 80 on which the magnet and the yoke have been positioned is covered with the second member 90, whereby a ring 91 provided to the second member 90 becomes engaged by engaging claws formed at the upper ends of upstanding pieces 81 provided to the first member 80. In so doing, vertical movement of the second member 90 relative to the first member 80 is restricted. Next, with the ring 91 engaged by the engaging claws of the upstanding pieces 81, the second member 90 is rotated by a small amount in the counterclockwise direction, to thereby mate a projecting boss (not shown), provided to the second member 90, with an interlocking slot (not shown) provided to the first member 80. In so doing, rotation of the second member 90 relative to the first member 80 is restricted. A ring 82 of the first member 80 and the ring 91 of the second member 90 form the main trunk of the disc clamper which clamps the yoke and the magnet.
In a configuration for a disc device disclosed in Japanese Laid-open Patent Application 2008-243303, a clamper is provided with a lower clamper and an upper clamper. As the assembly procedure for this clamper, firstly, the lower clamper and the upper clamper are overlapped in such a manner that the upper face of a projecting boss of the lower clamper and the bottom face of the basal portion of the upper clamper are abutting. In the disclosure, the upper clamper is then turned clockwise to bring about engagement between an engaging claw of the upper clamper and an engaging slot of the lower clamper, as well as to fit the boss of the lower clamper into a boss hole in the upper clamper, thereby preventing separation of the engaging claw from the engaging slot.
In a configuration for a disc device recited in Japanese Laid-open Patent Application 2007-265526, a clamper is provided with a resin plate and a metal plate. As the assembly procedure for this clamper, in the disclosure, the metal plate is disposed over the resin plate, and in this state the metal plate is then turned slightly toward the clockwise direction with respect to the resin plate, thereby catching three hooks of the resin plate onto three small holes in the metal plate, in order to link the resin plate and the metal plate to one another.
In a disc clamper of a design in which a ring (peripheral wall) forming the main trunk of a disc clamper provided to a first member is engaged by a projecting piece provided to a second member, thereby restricting vertical movement of the first member relative to the second member, the first member is covered by the second member in the above manner, thereby restricting vertical movement of the first member relative to the second member (simultaneously with respect to the covering).
On the other hand, in order to restrict rotation of the first member relative to the second member in a state in which vertical movement of the first member relative to the second member has been restricted in the above manner, it has been necessary to rotate the first member by a small amount (rotated counterclockwise in FIG. 6), to mate the projecting boss provided to the first member with the interlocking slot provided to the second member.
However, in the assembly process, attachment is deemed to be complete at the point in time that the first member is covered by the second member, and it sometimes occurs that attachment to the disc device occurs in a state in which rotation of the first member relative to the second member is unrestricted (a faulty assembly state).